Jason Anthony "The Athlete" MacDonald was born on June 3, 1975. He is a Canadian mixed martial artist who competes as a middleweight in the Ultimate Fighting Championship. Born and raised in Merigomish, Pictou County, Nova Scotia, MacDonald currently resides in Red Deer, Alberta and fights out of Edmonton, Alberta.

MacDonald made his UFC debut on October 10, 2006 at Ortiz vs. Shamrock 3: The Final Chapter with a win over The Ultimate Fighter 3 finalist Ed Herman via triangle choke in the first round. On December 30, 2006, at UFC 66, MacDonald defeated Chris Leben with a modified guillotine choke submission in the second round.

Other notable wins include victories over UFC veterans Joe Doerksen, Gideon Ray, and Bill Mahood. Before fighting in the UFC, MacDonald had tried out for The Ultimate Fighter reality television show on multiple occasions, but did not make the cut

At UFC 68: The Uprising on March 3, 2007, MacDonald fought former UFC middleweight champion Rich "Ace" Franklin in Franklin's return bout since losing his title. Franklin mounted MacDonald in the final seconds of round two, causing enough injury to MacDonald's left eye area that his corner advised him to throw in the towel, and Franklin was declared the winner.

At UFC 83 on April 19, 2008 MacDonald defeated Joe Doerksen via TKO (strikes) at 0:56 of the 2nd round. This win resulted in MacDonald being awarded a $75,000 bonus for Knockout of the Night.

There was controversy as he hit Doerksen with two hammer fists after the fight appeared to have already been stopped. In an interview the day after the fight, Jason explained that the referee admitted to making an error when he instructed Jason to keep going.

On August 9, 2008 at UFC 87 in Minneapolis, Minnesota, Jason lost to Demian Maia at 2:44 of the third round by rear naked choke.

Jason and his wife Kelly have four children, sons Tristin and Keel and daughters Jett and True.